On December 4, 2002, Californians for Alternatives to Toxics (CATs) sued the California Department of Pesticide Regulation (DPR) for failing to comply with the California Environmental Quality Act. The petitioners say that DPR failed to review impacts of pesticides widely found in Sierra amphibian habitat and linked to steep declines in California red-legged frog and other amphibians listed under the Federal Endangered Species Act.

The California Environmental Quality Act, (CEQA) requires DPR to re-evaluate pesticide registrations each year if new evidence is found of significant environmental impacts. The CATS petition asserts that DPR has failed to re-evaluate the registration of a number of pesticides implicated in the alarming frog declines. "The Department of Pesticide Regulation has known since 1993 that drift of insecticides applied to agricultural crops in the Central Valley has contaminated pristine areas of the Sierra Nevada, yet it has never investigated the extent of this pollution," said Patty Clary, Executive Director of CATs. "Nor has DPR responded when studies showed the extreme sensitivity of Sierran frogs to these chemicals, even while populations of these frogs are crashing."

Each year, roughly 156 million pounds of pesticides are applied to crops in the Central Valley, (figures for 2000) a portion of which are carried by winds into the seemingly pristine areas of the Sierra Nevada. Susan Kegley, PANNA Staff Scientist, notes, "Airborne pesticide movement is well documented. Drift is the only way those pesticides can get from the valley to the waters of the Sierra Nevada."

Rainwater brings drifting pesticides back to earth, where they are absorbed through the frogs' moist skin. Gary Fellers of the U.S. Geological Survey (USGS) characterizes frogs as "essentially environmental sponges, soaking up chemicals from water." A study by the USGS showed that frogs, in the Sierra, were exposed to organophosphates such as chlorpyrifos, malathion and diazinon (see the PAN Pesticide Database for information on each of these pesticides at http://www.pesticideinfo.org).

Populations of the red-legged frog, foothill yellow-legged frog, mountain yellow-legged frog and Yosemite toad have sharply declined over the past two decades, often disappearing from high elevation, seemingly pristine habitats in the Sierra. A recent U.S. Geological Survey study found organophosphate pesticides, including chlorpyrifos, malathion and diazinon, in Sierra amphibian habitats. Diazinon and chlorpyrifos have turned up in tissues of more than half of the frogs caught in Yosemite National Park and 86% of frogs tested in the Lake Tahoe area. A study by the California Water Quality Control Board found concentrations of diazinon in winter rainwater (collected when dormant orchards are sprayed) exceeded the lethal dose for at least one small invertebrate that is a food source by fish.

CATs' lawsuit is based on evidence that the pesticides detected are likely to disrupt the endocrine system, resulting in a variety of negative impacts on amphibian species. Among these are hormonally-caused alteration of normal sexual development or interference with amphibian immune systems, rendering them more susceptible to disease.

Of the four Sierra amphibian species currently in decline, the red-legged frog is already listed as threatened under the federal Endangered Species Act, while petitions to list the other three species have either already been submitted or are being prepared. The recent findings implicating pesticides in the decline of frog populations were also cited in a lawsuit against the U.S. Environmental Protection Agency (EPA) brought by the Center for Biological Diversity in April 2002. That suit accused the EPA of ignoring the federal Endangered Species Act by not restricting pesticides known to kill or deform the red-legged frog. The EPA has denied the allegations.

CATs claims that DPR, despite knowledge of recent studies that correlate the decline of Sierra frog populations with pesticide drift, disregarded procedure and simply re-registered chemicals such as diazinon, chlorpyrifos, malathion, parathion and endosulfan for another year of legal use. The suit also names California-licensed pesticide producers Dow Agrosciences LLC, FMC Corp., Gowan Co., Zeneca Inc., Platte Chemical Co., and Syngenta Crop Protection Inc. Additional pesticides drifting into Sierra environments include the herbicides glyphosate and triclopyr, which are sprayed in large quantities on both private and US National Forest lands in the Sierra (see PANUPS: Herbicides to Fight Forest Fires?, Sept 18, 2002).

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